3D bioprinting dermal-like structures using species-specific ulvan.

3D bioprinting has been increasingly employed in skin tissue engineering for manufacturing living constructs with three-dimensional spatial precision and controlled architecture. There is however, a bottleneck in the tunability of bioinks to address specific biocompatibility challenges, functional traits and printability. Here we report on a traditional gelatin methacryloyl (GelMA) based bioink, tuned by addition of an ulvan type polysaccharide, isolated from a cultivated source of a specific Australian Ulvacean macroalgae (Ul84). Ul84 is a sulfate- and rhamnose-rich polysaccharide, resembling mammalian glycosaminoglycans that are involved in wound healing and tissue matrix structure and function. Printable bioinks were developed by addition of methacrylated Ul84 (UlMA) to GelMA solutions. The inclusion of UlMA in the bioinks facilitated the extrusion printing process by reducing yield stress. The resultant printed structures containing ulvan exhibited improved mechanical strength and regulated the rate of scaffold degradation. The 3D printed cell-laden structures with human dermal fibroblasts demonstrated high cell viability, support of cell proliferation and dermal-like properties as evidenced by the deposition of key dermal extracellular matrix components including collagen I, collagen III, elastin and fibronectin. In vitro degradation suggested the role of UlMA in supporting structural stability of the printed cellular structures. Taken together, the present work demonstrates progression towards a biocompatible and biofunctional ink that simultaneously delivers improved mechanical, structural and stability traits that are important in facilitating real world applications in skin tissue repair.